Abstract The paper presents the results obtained for aqueous solutions of a mixture of cocamidopropyl betaine (CAPB) and sodium dodecyl sulfate (SDS) in rheological tests in the shear and extensional flow. The rheological measurements in the extensional flow were conducted using a capillary breakup extensional rheometer. The description of the mechanical spectra required the application of the multi-mode Maxwell model, which demonstrates that stress relaxation occurs via reptation – as in entangled polymer solutions. The rheological properties of aqueous CAPB/SDS solutions in the extensional flow were also found to be qualitatively consistent with the properties of entangled polymer solutions. The ratio of the extensional relaxation time to the transient shear relaxation time was considerably lower than one, and the range of elasto-capillary thinning appeared at a Weissenberg number of 2/3. The difference between polymer solutions and CAPB/SDS solutions is noted at late times, when the transient extensional viscosity of the solutions of polymers and wormilke cationic surfactants reaches a constant value, whereas in CAPB/SDS solutions it drops rapidly. The decrease in transient extensional viscosity in this range may be due to the break-up of wormlike micelles under the influence of high transient extensional stresses. Graphical Abstract

中文翻译：

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椰油酰胺丙基甜菜碱和十二烷基硫酸钠混合物水溶液的剪切和拉伸流变学

摘要 本文介绍了椰油酰胺丙基甜菜碱 (CAPB) 和十二烷基硫酸钠 (SDS) 混合物的水溶液在剪切流和拉伸流中的流变测试结果。拉伸流中的流变测量使用毛细管破裂拉伸流变仪进行。机械谱的描述需要应用多模麦克斯韦模型，该模型表明应力松弛通过蠕动发生 - 如在缠结的聚合物溶液中。还发现在拉伸流动中 CAPB/SDS 水溶液的流变特性与缠结聚合物溶液的特性在性质上一致。拉伸弛豫时间与瞬态剪切弛豫时间之比大大低于 1，并且弹性毛细管变薄的范围出现在魏森伯格数为 2/3 处。聚合物溶液和 CAPB/SDS 溶液之间的差异是在后期注意到的，当聚合物溶液和 wormilke 阳离子表面活性剂溶液的瞬时拉伸粘度达到恒定值时，而在 CAPB/SDS 溶液中它迅速下降。在此范围内瞬时拉伸粘度的降低可能是由于蠕虫状胶束在高瞬时拉伸应力的影响下破裂所致。图形概要 在此范围内瞬时拉伸粘度的降低可能是由于蠕虫状胶束在高瞬时拉伸应力的影响下破裂所致。图形概要 在此范围内瞬时拉伸粘度的降低可能是由于蠕虫状胶束在高瞬时拉伸应力的影响下破裂所致。图形概要